Markus Nauck

Human Connective Tissue Growth Factor Is Expressed in Advanced Atherosclerotic Lesions

BACKGROUND Atherosclerosis affects certain but not all vascular beds of the human circulation. Its molecular mechanisms are only partially understood. Human connective tissue growth factor (hCTGF) is a novel cysteine-rich, secreted polypeptide. hCTGF is implicated in connective tissue formation, which may play an important role in atherosclerosis. METHODS AND RESULTS By using a differential cloning technique, we isolated a cDNA clone from a human aorta cDNA library, which is identical to hCTGF. Northern analysis shows that hCTGF mRNA was expressed at 50- to 100-fold higher levels in atherosclerotic blood vessels compared with normal arteries. In vascular smooth muscle cells, high-level expression of hCTGF mRNA was induced by transforming growth factor-beta 1. Using in situ hybridization and immunohistochemistry, we found that all advanced atherosclerotic lesions of human carotid arteries (eight patients; mean age, 69; age range, 57 to 85 years) and femoral arteries (two patients; mean age, 71.5 years) that we tested expressed high levels of both hCTGF mRNA and protein. hCTGF expression was localized mainly to smooth muscle cells in the plaque lesions that are negative for proliferating cell nuclear antigen staining. In addition, some CD-31-positive endothelial cells of plaque vessels expressed high levels of hCTGF mRNA and protein. hCTGF-positive cells were found predominantly in areas with extracellular matrix accumulation and fibrosis. In contrast, in normal arteries, we were unable to detect either hCTGF mRNA or immunoreactive hCTGF protein. CONCLUSIONS In the present study, we have shown for the first time that both hCTGF mRNA and protein are expressed in human arteries in vivo and that hCTGF may represent a novel factor expressed at high levels specifically in advanced lesions and may play a role in the development and progression of atherosclerosis.

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), &bgr;-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, &bgr;-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.

Interleukin-6 Stimulates LDL Receptor Gene Expression via Activation of Sterol-Responsive and Sp1 Binding Elements

Inflammatory or malignant diseases are associated with elevated levels of cytokines and abnormal low density lipoprotein (LDL) cholesterol metabolism. In the acute-phase response to myocardial injury or other trauma or surgery, total and LDL cholesterol levels are markedly decreased. We investigated the effects of the proinflammatory cytokine interleukin (IL)-6 on LDL receptor (LDL-R) function and gene expression in HepG2 cells. IL-6 dose-dependently increased the binding, internalization, and degradation of (125)I-LDL. IL-6-stimulated HepG2 cells revealed increased steady-state levels of LDL-R mRNA. In HepG2 cells transiently transfected with reporter gene constructs harboring the sequence of the LDL-R promoter extending from nucleotide -1563 (or from nucleotide -234) through -58 relative to the translation start site, IL-6 dose-dependently increased promoter activity. In the presence of LDL, a similar relative stimulatory effect of IL-6 was observed. Studies using a reporter plasmid with a functionally disrupted sterol-responsive element (SRE)-1 revealed a reduced stimulatory response to IL-6. In gel-shift assays, nuclear extracts of IL-6-treated HepG2 cells showed an induced binding of SRE binding protein (SREBP)-1a and SRE binding protein(SREBP)-2 to the SRE-1 that was independent of the cellular sterol content and an induced binding of Sp1 and Sp3 to repeat 3 of the LDL-R promoter. Our data indicate that IL-6 induces stimulation of the LDL-R gene, resulting in enhanced gene transcription and LDL-R activity. This effect is sterol independent and involves, on the molecular level, activation of nuclear factors binding to SRE-1 and the Sp1 binding site in repeat 2 and repeat 3 of the LDL-R promoter, respectively.

Low-Density Lipoprotein Triglycerides Associated With Low-Grade Systemic Inflammation, Adhesion Molecules, and Angiographic Coronary Artery Disease The Ludwigshafen Risk and Cardiovascular Health Study

Background—Markers of systemic inflammation and LDL cholesterol (LDL-C) have been considered independent risk factors of coronary artery disease (CAD). We examined whether alterations of LDL metabolism not reflected by LDL-C were associated with low-grade inflammation, vascular injury, and CAD. Methods and Results—We studied 739 subjects with stable angiographic CAD and 570 matched control subjects in which CAD had been ruled out by angiography. The association of LDL triglycerides (LDL-TGs) (odds ratio [OR], 1.30; 95% CI, 1.19 to 1.43; P<0.001) with CAD was stronger than that of LDL-C (OR, 1.10; 95% CI, 1.00 to 1.21; P=0.047). The predictive value of LDL-TG for CAD was independent of LDL-C. “Sensitive” C-reactive protein (CRP), serum amyloid A, fibrinogen, interleukin 6, intercellular adhesion molecule-1 (ICAM-1), and vascular adhesion molecule-1 (VCAM-1) increased in parallel to LDL-TG. CRP, ICAM-1, and VCAM-1 were inversely related to LDL-C. To examine whether LDL-TGs were associated with the distribution of LDL subfractions, we studied 114 individuals with impaired fasting glucose, impaired glucose tolerance, or type 2 diabetes mellitus. In subjects with high LDL-TG, LDLs were depleted of cholesteryl esters (CEs), and VLDLs, IDLs, and dense LDLs were significantly elevated. Conclusions—Alterations of LDL metabolism characterized by high LDL-TG are related to CAD, systemic low-grade inflammation, and vascular damage. High LDL-TGs are indicative of CE-depleted LDL, elevated IDL, and dense LDL. LDL-TG may better reflect the atherogenic potential of LDL than LDL-C.

Effect of atorvastatin, simvastatin, and lovastatin on the metabolism of cholesterol and triacylglycerides in HepG2 cells.

We evaluated the effects of the hydroxymethylglutaryl coenzyme A reductase inhibitors (HMGRI) atorvastatin, lovastatin, and simvastatin on lipid homeostasis in HepG2 cells. The drugs were almost equally effective in inhibiting cholesterol synthesis and in decreasing cellular cholesterol. Atorvastatin and lovastatin increased low-density lipoprotein receptor mRNA (2.5-fold at 3 x 10(-7) M) and the transcription rate at the promoter of the low-density lipoprotein receptor gene (>5-fold at 10(-6) M). The three compounds enhanced the activity of the low-density lipoprotein receptor at a similar magnitude (1.6-2.1- fold at 10(-6) M). Atorvastatin and lovastatin increased the nuclear form of sterol regulatory element binding protein (SREBP)-2, but not of SREBP-1. Each of the drugs increased triacylglyceride synthesis (50% at 10(-7)-10(-6) M), cellular triacylglyceride content (16% at 10(-6) M), and expression of fatty acid synthase by reporter gene and Northern blot analysis (2-fold and 2.7-fold at 10(-6) M and 3 x 10(-7) M, respectively). All compounds reduced the secretion of apo B (30% at 3 x 10(-7) M). HMGRI decreased the ratio of cholesterol to apo B in newly synthesised apo B containing particles by approximately 50% and increased the ratio of triacylglycerides to apo B by approximately 35%. We conclude that regulatory responses to HMGRI are mediated by SREBP-2 rather than by SREBP-1, that HMGRI oppositely affect the cellular cholesterol and triacylglyceride production, that HMGRI moderately decrease the release of apo B containing particles, but profoundly alter their composition, and that atorvastatin does not significantly differ from other HMGRI in these regards.

Cord Blood Levels of Interleukin-6 and Interleukin-8 for the Immediate Diagnosis of Early-Onset Infection in Premature Infants

Background: Cytokine plasma levels are suggested to be sensitive indicators of neonatal sepsis, but conventional assays are time consuming. This study aimed at evaluating the significance of cord blood levels of interleukin (IL)-6 and IL-8 determined by a fully automated random access assay within 90 min of admission to predict systemic bacterial infection. Patients and Methods: Cord blood levels of IL-6 and IL-8 were determined in 71 mature and 100 premature infants by a chemiluminescence assay (Immulite®). Patients were divided into four groups according to a clinical and laboratory scoring system. Group A: documented early-onset infection; group B: infection possible; group C: infection unlikely, and group D: healthy newborns. Results: Median IL-6 levels in the subgroup of premature newborns were as follows: group A, 1,920 pg/ml (5–95% confidence interval 308–4,660 pg/ml); group B, 50 (15–102) pg/ml; group C, 21 (12–71) pg/ml, and group D, 8 (6–11) pg/ml. For IL-8, median levels for groups A–D were 289 (226–514) pg/ml, 87 (40–107) pg/ml, 44 (33–98) pg/ml and 21 (16–25) pg/ml, respectively. The difference between group A and the other groups was highly significant (IL-6 p < 0.0001, IL-8 p < 0.001). At a cut-off of 80 pg/ml, the sensitivity of IL-6 for the diagnosis of sepsis was 96% (specificity 95%). For IL-8 (cut-off 90 pg/ml), the sensitivity was 87% (specificity 94%). Conclusion: In premature infants, the diagnosis of an early-onset infection can be established or ruled out with a high level of confidence by measuring IL-6 or IL-8 levels from cord blood using a random access chemiluminescence assay.

Haplotypes of the cholesteryl ester transfer protein gene predict lipid-modifying response to statin therapy.

ABSTRACTCholesteryl ester transfer protein (CETP) plays a central role in high-density lipoprotein (HDL) metabolism. Single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were determined in 98 patients with untreated dyslipidemias and analyzed for associations with plasma CETP and plasma lipids before and during statin treatment. Individual CETP SNPs and haplotypes were both significantly associated with CETP enzyme mass and activity. However, only certain CETP haplotypes, but not individual SNPs, significantly predicted the magnitude of change in HDL cholesterol (HDL-C) and triglycerides. After adjusting for covariates and multiple testing, the TTCAAA haplotype showed a gene-dose effect in predicting the HDL-C increase (P=0.03), while the TTCAAAGGG and AAAGGG haplotypes predicted a decrease in triglycerides (P=0.04 both). This is the first study to demonstrate that SNP haplotypes derived from allelic SNP combinations in the CETP gene were more informative than single SNPs in predicting the response to lipid-modifying therapy with statins.

Genotype-corrected reference values for serum angiotensin-converting enzyme

The deletion (D)/insertion (I) polymorphism in intron 16 of the angiotensin-converting enzyme (ACE) gene has the greatest impact on serum ACE level in Caucasians of any factor yet discovered. The aim of the present study was to establish new ACE genotype-corrected normal ranges for serum ACE level in a population of central European origin. After a medical examination, 159 healthy Caucasians volunteered to donate blood for the study. ACE genotypes were assessed by PCR and serum ACE levels were determined using two different kinetic tests. The distribution of the D/I polymorphism of the ACE gene was in accordance with the Hardy–Weinberg equilibrium. Serum ACE levels and ACE genotypes correlated significantly, with the highest serum ACE levels in subjects with ACE genotype D/D, and the lowest serum ACE levels in subjects with genotype I/I (mean±sd, assay 1: D/D 59.3±15.1 U·L-1, D/I 45.5±15.2 U·L-1, I/I 34.8±13.7 U·L-1; assay 2: D/D 43.7±14.1 U·L-1, D/I 33.7±12.1 U·L-1, I/I 25.4±9.5 U·L-1). Although they gave different absolute values of serum ACE levels, the results of the two test kits correlated significantly. In conclusion, the present authors recommend the use of new, genotype-specific reference values for serum angiotensin-converting enzyme levels, especially to improve the sensitivity and specificity of tests for angiotensin-converting enzyme in the follow-up of sarcoidosis.

G(−30)A Polymorphism in the Pancreatic Promoter of the Glucokinase Gene Associated With Angiographic Coronary Artery Disease and Type 2 Diabetes Mellitus

Background—Type 2 diabetes mellitus (T2DM) increases the risk of coronary artery disease (CAD). A G(−30)A polymorphism in the β-cell–specific promoter of glucokinase (GK-30PM) has been implicated in reduced pancreatic β-cell function. Its impact on CAD has not been examined. Methods and Results—The glucokinase G(−30)A variant was determined in 2567 patients with angiographic CAD and in 731 individuals in whom CAD had been ruled out by angiography. In carriers of the A allele, the adjusted OR of CAD was 1.39 (95% CI, 1.15 to 1.70). Corresponding ORs were 1.27 (95% CI, 1.02 to 1.59) and 1.92 (95% CI, 1.26 to 2.93) in individuals without and with T2DM, respectively. The prevalence of the A allele increased in parallel with the Friesinger coronary score. Patients with T2DM were more frequent among carriers of ≥1 A allele (OR, 1.17; 95% CI, 1.00 to 1.28). This association was stronger if CAD patients only were considered. The A allele was associated with higher glucose (fasting, P =0.002; 2 hours after oral glucose, P =0.017) and glycohemoglobin (HbA1c; P =0.002). Furthermore, presence of 1 A allele was negatively related to β-cell function, estimated by β percent (P =0.012) and by the ratios of proinsulin to insulin (P =0.025) and proinsulin to C peptide (P =0.019). Conclusions—The A allele of the pancreatic promoter of glucokinase increases the risk of CAD in individuals with and without T2DM. Furthermore, at least in CAD, it is associated with an augmented prevalence of T2DM.